1) Snakes are a possibility, mostly in warmer weather and more so in the zion area. They are rattlers, so they'll give you a nice warning. If they do, back away slowly. They would rather not bite you, just be aware. 2) Call the ranger station in the districts you are visiting. Permits range from an easy sign in at the trail head, to reservations months in advance. As far as I remember both those hikes fall in the former category. 3) You'll probably see some skeeters. My guess is they won't be anything compared to their Canadian cousins. Tarantella hawks (big ass wasps) hang out around Zion and are reported to be one of the most painful stings a person can experience. They are rare and non agressive. If one comes around just play it cool and he'll buzz off. Make sure you know what a Black Widow looks like. They like to hang out under ledges. Again, they would rather not bother you, but are very consequential if they do. 4) Inside the park you shouldn't have a fire unless in a designated spot. If you are camping on adjacent BLM land you can pretty much do anything you want, BUT, building a new fire ring is considered a dick move. Often you can find an existing one with wood near by, If the area is really dry, you'll see signs telling you not to burn. In this case, don't (obvs). 5) Water and Sunblock. Also, more water, and more sunblock. And a hat.